Signal device and projector therefor.



/ ME L TCHISO I SIGNAL DEVICE AND PROJECTOR THEREFOR.

' I 1 APPLICATION FILED APR.6.19II. 15149 583, -Patented u -:10, 1915..

5 SHEETS-'SHEET I- I, I v @311 Maine? M. R. HUTCHISONJ SIGNAL DEVICE'AND P ROJECTOR THEREFOR. APPLICATION FILED APR. 6, 191' 1 149 588 PatentedAug.10,1915.

5 SHEET HEET,2.

' M. R. HUTCHISON- SIGNAL DEVICE AND PROJECTOR THEREFOR. APPLICATION FILED APR. s, 19H. 1 149 583, Patented Aug. 10, 191E 5 SHEETSSHEEIIT 3'.

wi/tvwooao M. R.- HUTCHISONR SIGNAL DEVICE AND PROJECTOR THEREFOR. I APPLICATION FILED APR. 6. 19H.

. PatentedAi 1g.10,l915.

M. R. HUTCHISON. SIGNAL DEVICE AND PROJECTOR THEREFOR.

APPLICATION FILED APR. 6, 19 1 1..

Patented Aug. 10, 1915.

' 5 SHEETS -SHEET 5.

wivinlt. W212i;

as an ric,

MILLER REESE HUTCIEISON, 0F SUMMIT, JERSEY, ASSIGNOR T0 LQVELL- MGCONNELL MANUFACTURING COMPANY, A CORPORATION OF DELAWARE.

, SIGNAL DEVICE AND PROJECTOR THEREFOR. I

wastes.

Specification of Letters Ilatent.- Patented Aug. 1@, 1915..

Application filed April 6, 1911. Serial a... 619,267.

To all whom it may concern: I

Be it known that I, MILLER REESE HUTCHI- son, a citizen of the United States, and resident of Summit, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Signal Devices and Projectors Therefor, of which the following is a specification.

This invention relates to improvements in sound producing instruments operating on the principle of a siren, particularly such as are adapted for alarms or signals on automobiles, motor boats, and other vehicles, or for factories, fire alarms, fog signals, etc. The invention was devised, primarily, with reference to sirens of the type in which the required initial air. pressure is produced by a high-speed fan or centrifugal blower, and in which the relatively movable cut off openings, whichproduce the air pufiz's and sound waves characteristic of the siren, are circularly arranged on a circle or on a cylinder of considerable circumference. In one of the well known devices of this sort, sometimes 3 used on automobiles, the relatively movable members are cylindrical and the puff proin certain cases only one of the cylindrical apertured members is movable, and is secured to and carried by the fan itself.

According to my invention, Iprovide a siren with an annular pro ector or amplifier adapted to direct the sound waves for-' wardly. This is particularly applicable to sirens of the type in which the outgoing puffs-0f air are allowed to escape radially, though it is equally applicable to any siren construction in which the openings referred to are circularly or annularly arranged so that the puffs escape at the face of the device instead of at the periphery. In any such case, the inner annular wall of my projector tends to prevent dissipation and distortion of the sound waves in the dead space within the circle formed by the innermost portions of the outlet openings. A further refinement of this feature consists in filling in the dead spaces between the adjacent outlet openings on the exit side, so that each outgoing puff of air, and the acoustic wave generated thereby, is propagated and directed through a smoothly expanding passage until they gradually mergeand are har moniously projected, preferably forwardly rather .than radially. This improvementobjectionable, insorfiuch as the sound waves have to be elastically propagated across and against the indrawn current of air. Moreover, each sound wave, as it leaves the projector, bein annular, is less unitary and definite and is more distorted than is desirable. Hence I prefer to carry the inner walls of the projector to a point, so that the annular sound Wave, upon leaving the projector, has a more clean-cut and definite wave front extending across the entire area inclosed by the outermost walls of the projector. This arrangement involves entire separation of the functions of air inlet and sound projector, and in practice, I prefer to arrange the air inlet on the rear side of the fan; that is, on the side opposite that from which the sound is projected.

One of the main faults of the siren, as an automobile signal, has been that its note was smooth and musical, instead of having the compelling quality desirable for a warning signal. I find that I can largely obviate this defect by making the apertures, in the relatively rotatable members, short inthe direction of movementand elongated in a transverse direction; sothat with the same pressure, and with the same volume of air in each pufi, the escape and cut-off much sharper than where the openings are squareor elongated in the direction of mmcment.

be called the rotor, and the stationary member the stator. The rotor, as commonly constructed, 1s a combination of centrifugal fan and an annular cut-off member, mounted on the'periphery of the fan and provided v with'apertures which alternately coincide and blank with the apertures in the stator.

loudness, on the other hand. I find that this difiiculty may be obviated by separating the fan and the rotary cut-off, so that the fan mayrotate as a fan alone, without the ne-- cessity of a close peripheral fit between the same and the stator. The rotary cut-off may ngw be drivenloy the same means as the fan, orby separate means, preferably the latter, as a muchmoreeifective control can be had in this Way. The best arrangement is one in which the stator, or member containing the stationary openings, is interposed between the fan, on the inside, and rotary cutoff, on the outside.

Another object of my invention is, to proide means whereby any motor-operated instrument, having a wailing or rising and falling sound, may be improved, by synchronizing the normal pitch or frequency of the note with the natural or resonant pitch of the projector. This has the further advantage of giving a maximum output of sound for a given power expended. This governing-of the normal frequency of the note may be accomplished, either by causing a disproportionate increase of work done, or decrease of power to the motor, for all speeds beyond the resonant frequency. I prefer the expedient of cutting down the power of the motor, and in the case of an electric motor, I employ automatic controlling means, governed by the loudness of the sound waves of the resonant air column of the projector, and operating to cut. down the current supply to the motor, when the speed tends to exceed the speed at which the note produced is the resonant note ofprojector. Such means may be widely varied. An illustrative embodiment is one in which a suitable carbon transmitter or microphone is employed, which allows less current to pass whenthe amplitude of vibration of its dia-' puffs of air longitudinally of the projector,

vention, I shall now proceed to describe certain specific embodiments thereof, reference being had to the accompanying drawing. in which Figure 1. is a longitudinal section through a siren signal, the driving motor being conventionally illustrated. Fig. 2 is a trans verse section through the fan and the relatively rotatable cut-off members. Fig. 2-) is a side view of one of the cut-off members. Fig. 4 is a view similar to Fig. 1 showing a form of siren signal in which the intake and projector are disposed at opposite sides. Fig. 5 is a view somewhat similar to Fig. l but showing a form of siren with independ ent fan and cut-off. Fig. 6 is a cross-section through the base of the projector-shown in Fig. 5 and theparts therein. Fig. 7 is a detail enlarged interior view of a portion of the projector showing filler strips occupying the dead spaces therein. Figs. 8 and 9 are longitudinal sections through similar signals showing varied forms of projector.

The signal shown in Fig. l comprlses a siren, in which the relatively movable members consist of a rotary member 2 and a stationary encircling member 3, provided in its periphery with apertures 4. In this case, the rotary member includes a centrifugal fan 5 and an annular cut-oil 6 fixed at the ends of the fan blades 8 and provided with a series of apertures 7 corresponding to the series of apertures in the stationary memher. well understood. The shaft 9 of the rotary member will be mounted in suitable bearings and may be driven by any suitable means, such as an electric motor 20.

The siren proper is inclosed by a projector, adapted to direct the sound parallel to the axis of rotation, and this projector is distinct from the inlet to the siren. The construction of the projector maybe considerably varied, but the air column thereof is preferably annular. It may consist of an outer horn 10 and an inner. wall 12, with the annular air column between them. The siren is inclosed within the base of the an The action of such an assemblage is was . nular projector, and the stationary member 3 may form part of the inner wall thereof. The length of this projector is such that the annular air column thereof is resonant to a note of the frequency which will be produced when the rotor is running at normal speed. The cross-section of the annular'air column isproportioned in accordance with the combined volume of the puffs which the siren is capable of emitting at each opening of the apertures, and it increases in cross- .section towardthe' front, to allow for the expansion following the compression due to theentering pufi's. Wall of-the horn 10- diverges in a forward direction, whereas the inner wall ofthe horn 12 converges in the same direction.

In Fig. 1, the air inlet for the siren is arranged within the inner horn 12, so that the entering air and the projected sound waves travel in opposite directions' The passage thus formed ,for 'the entering air may be cylindrically defined by a wall 13 and is ample in cross-section, as is also the opening in the front of the fan. The space between walls 12 and 13 is closed by an annular wall close. to and parallel with the front edges of the blades of the fan.

The apertures 4 and 7 in the rotor and in the stationary member respectively, are preferably similar, and are constructed so as to produce more abrupt puffs of air,

thereby generating sharper and more 1ntense sound waves than is customary in s1- rens. To this end, as shownln Flgs. 3 and 14, they are made narrrow in the direction of movement of the relatively rotatablemembers, and correspondingly long transversely to such-direction, moreover, they are spaced apart at distances materially greater than their widthg Thisfo'rm and arrangement of apertures-is preferably employed in all the forms of the: invention."

A more startlingeffect may be secured by I irregularly spacingthe apertures, as in Fig.

14, wherein are shown portions-of the pemembers in which this feature is embodied, it being assumed}that the development of the respectiveperipheries "would show reguripheries" be relatively movable cut-off lar" repetitipns spacing shown in this view. --Injthisi.arrangement,- coincidence of one set ofapertures 143, 9", 4 with apertures 7 7H7, produceadominant or' fundamental note, :butwhen 73. coincides with 4:, another puff takes place, and immediately after 7.coin'cides with 4 giving another "'pufl; Theseand similar intermediate pufis are superposed on the dominant or funda mental note. The spaces could be so ar-' ranged that the intermediate puffs can be I harmonics of the fundamental, or vice versa;

but this effect is sometimes too harmonious andfor warning purposes the best results will probably be attainable by irregularly To this end, the outer distributing the openings, so that a harsher or moreragged sound is produced.

The arrangement of projector and air-intake, described in connection with Fig.- 1, permits of producing and directing sound in a very eflicient mannertbut owing to the proximity of the mouth of the projector to the stream of air' entering the intake, there is a tendency to distortion and attenuation of the sound waves, due to the draft across the mouth of the projector and to the dead space thus presented at'the center'of the annularly propagated sound waves. In Fig. 4:, I show how this difliculty may be avoided, by closing in the air passage, preferably by shaping the inner walls of the projector sothat they converge to a point. This permits the annular sound waves to be projected more effectively. This arrangement is of particular value when the intake, 13 is placed at the rear of the device, at the opposite side fromthe .forwardly extending projector.

In such case, it is better pfro-" tected from rain, dirt, flying stones etc., and

can be made short,as shown,' so as to afford less obstruction to the air supply. The separation of the intake and projector has a further material advantage, in that it'permits me to close the inner wall 12 of theprojector, at the front-,thereby forming an inclosed chamber. or casing, in which a motor 20 for driving the fauand rotatable aperture'd-member may begiiistalled. Thus, an extremely .compactde f m'ay be ob- In lI'haveshown aistillfurther development 'ofjthe invention, inv which the aim-forcing means. and .the rotary cutoff rately driven. Here. the fan 5 does not have the: annular cut-ofl'F'fi ed to its .periphery, -.but operates -to force the air "against the sta- 'tionary cut-off member 3. The rotary cutthrough suitable connectionssuch as a shaft 22 and a spider. 23. It will be clear that, owing to the separation of the air-forcing means and the rotary cut-off, the fan may be dispensed with and the compressed air or other fluid supplied from any suitable source. This view shows also how the. device may be throttled and the sound controlled while the rotary parts continue to. run at 'speed. Such arrangement may be utilized for turning on or off or modulating the ordinary warning 'note or for sending code messages, or for -member are separated, and preferably sepahorn and an arm or link 27 for engaging stationary cutoff .member.

therewith. As will be readily understood, when the openings in the sleeve coincide with the apertures 4 in the stator, the sound is not afiecte'd; but as the sleeve is turned to cover the openings more and more, the sound willfdecrease until it is cut off entirely, though the rotary cut-ofi and fan continue to run. In Fig. 12, I have illustrated the same form of rotatable throttling sleeve mounted to turn on the outside of the This arrangement will be particularly applicable to those forms in which the rotary cut-off is inside the stationary member and is carried by the fan. i Fig. 11 shows another form of device for throttling the puffs of air, the same consisting of a solid endwise slidable sleeve 25*. Fig. 10 illustrates a throttle adapted to act on the incoming air, the same being shown for purposes of illustration as in the hinged shutter 25* cooperating with the intake.

In Fig. 4, I have illustrated a very care fully designed fan construction for siren purposes. The blades 8 are deep in an axial direction and short radially, permitting of a very ample intake 13 without sacrifice in the capacity of the fan. Moreover, the fan blades 8 are curved, and in practice the curvature will be such as to produce the most eflicient air-forcing action.

Figs. 6 and 7 likewise illustrate an embodiment of means for preventing lateral eddying of the pufi's of ,air in the annular projector, at the region of the openings by which the air enters the projectors. This is accomplished, in the particular construction illustrated, by means of fillers 30, arranged in a circular series, so as to fill the portions of the interior of the projector, between the air openings in the stationary member of the cut off. The result of this provision is, the puffs of air, on entering the projector, are barred from spreading sidewise, the only movement possible being in a forward direction. The spaces between these fillers should be proportioned, so that the fillers may taper and' the air passages diverge and finally merge into the annular interior of the projector.

In all-the forms of the invention so far discussed I have shown the projector as being provided with an annular deflecting surface 35, preferably arranged at a 45 angle,

nally of the projector.

for impingement of the waves or puffs from the openings of the relatively rotatable cut off members, and to direct them longitudi- Instead of being straight in cross-section, this annular surface may be curved, as shown in Fig. 8. Or, instead of being comparatively wide at the base, the interior of the projector may be narrow, as shown in Fig. 9, the inner and outer walls of the projector forming a comparatively acute angle.

Fig. 5 shows one embodiment of means for holding the siren to resonance. This means includes a suitable carbon microphonic re-- sistance 40, which may be of the telephone transmitter type capable of carrying considerable current, said resistance being interposed in the supply circuit, or a controlling circuit for the motor which drives the otary cut ofl". The microphonic resistance includes a body made up of loose particles which body may transmit an electric current at all times but may transmit it'with less resistance when the particles are in vibration. This microphonic resistance is exposed to the action of the sound waves produced by the instrument, and the diaphragm which holds the particles in place is vibrated by the sound waves and by its vibrations agitates the particles so that their resistance changes in response to the sound vibrations. Thus when the note produced by the siren is in synch ronism with the resonator, the amplitude of vibration given the diaphragm of the transmitter will be a maximum, and the amount of current permitted to pass will also be a maximum; but that when the speed tends to exceed that required for resonance, the diminution of sound, through decreasing resonance, will result in less diaphragm vibration, thus increasing the resistance and keeping down the speed of the motor and the rotating parts, so that the note of the Siren will be maintained approximately at resonance. This action may be made more pronounced by tuning the vibratory diaphragm so that it will respond to the resonant frequency and vibrate more violently to a note of that frequency than to much louder notes of other frequencies. Numerous other forms of automatic means susceptible to the sound vibrations from the'resonator may be employed for the purpose.

I claim 1. A siren signaling device, comprising 'relatively rotatable inner and outer members, one of said members having openings and the other of said members adapted to open and close said openings as said members are relatively driven, and annular soundprojecting means communicating with said openings and having inner and outer walls,

. the inner walls beingclosed upon each other at the front.

'2. A siren signaling device, comprising ing with the outlet side of said members-and 'tion.

having outer and inner walls, the latter convergingsubstantially to a point. ,7

3. A siren signaling device, comprising relatively rotatable cut-off members, one of said members having openings and the other of said members being adapted to open and close said openings as said members are relaively rotated, sound-projecting means com municating with said openings and having inner and outer Walls inclosing a hollow air column between them, and driving means within the inner walls.

4. A .siren signaling device, comprising relatively'rotatable members, one of said members having openings and the other of said members being adapted to open and close said openings as said members are relatively rotated, a driving motor, and soundprojecting means surrounding said motor and inclosing a hollow air-column with Which said openings establish communica- 5. A siren signaling device, comprising relatively rotatable 'cut-ofi members, means for relatively driving said members at high speed, a centrifugalfan separate from said members and having an ample air inlet, and anannular pro ector distinct from said 1nletand communicating ,with the outlet side of said members.

6. In a siren signalingdevice, a projector, a member having a circular seriesof openings delivering to said projector, rotatable means .for opening and closing said openings, means for driving said means,- and means for preventing transverse eddying in the projector at the region of the openings.

u 7. having a circular series of openings, rot-atable means for opening and closing said openings and means for driving said means,

an annular projector arranged to communicate at the inner side of its basal portion 1 with said openings, and an annular series of fillers occupying the. dead spaces .in the basal portion of the'projector.

@ '8. In a.- siren signahng devlce, an annular projector; a member having openings de- In a siren signaling device, a member- I projector, rotary means for opening and closing said openings, and a circular series of fillers-in the'basal portion of the projector barring the entering puffs-of air against lateral spreading, the spaces between said fill-,

ers flaring'forwardly and mergingwith the and an annular annular chamber of the forward part of the proj ector."

10. In a siren signaling device, a fan, a

stator adjacent the fan and provided With 1 an annular series of openings, and a cut-0E rotor on the other side of the stator. and

adapted to blank and uncover said openings.

,tured member, a fan .forforcing air to pass 11. In a siren signaling device, an aper-- therethrough, and a separately driven' r.o-

tary cut-ofi' member.

' '12. In a'siren signaling device, a fan for producing. the initialair pressure, and 'separately driven relatively v rotating apertured cut-off means.

13. In a siren signaling-device, a siren, a

resonator, a rotary electric motor for driving the siren, and means susceptible tothe sound .vibirations for controlling the-speed of the motor.

1a. In 'a siren signaling device, relatively rotatable members, one of said members having openings and the other. of said members adapted toblank and open said open ings, with said openings, and means controlled by. the vibrating ai r-column.=foi' preventing said member materially exceeding the speed which produces a note-synchronous with the resonator.

Signed at New York city, in the .,county of 18th day of March, 'A. 1911.

Witnesses:

IRVING M. OBRIE HT, GEORGE C. DEAN.

a resonator arranged to communicate York, and State of New York, this 

